# score_transition

Score how well one catalog track mixes into another (0-100) — the pairwise DJ transition score no raw key/BPM API gives you. Combines Camelot-wheel key compatibility, octave-aware BPM proximity (half/double-time counts as a match), and energy smoothness. Returns the overall score, per-component scores (harmonic/tempo/energy), a detail block (key_relation, both Camelot keys, both BPMs, bpm_delta, bpm_octave_matched, both energies, energy_delta), and a one-line human reason (e.g. "8A->9A adjacent (+1), 126->128 BPM (+2), energy +0.04 — clean uplifting mix"). Both ids are catalog itunes_track_ids — get them from search_catalog or the itunes_track_id field of a get_audio_features result. Costs 1 quota unit.

Agent View of the PolicyLayer registry record for `score_transition`. HTML page: https://policylayer.com/tools/com-freqblog-music-metadata/score-transition

## Facts

- Tool: `score_transition`
- Server: FreqBlog Music Metadata (`https://mcp.freqblog.com/mcp`) — https://policylayer.com/tools/com-freqblog-music-metadata.md
- Homepage: https://github.com/https://mcp.freqblog.com/mcp
- Risk category: Read (Low risk)
- Registry record: grade D, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 2 (2 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `to_track_id` | string | yes | The candidate track you're mixing INTO — a catalog itunes_track_id. |
| `from_track_id` | string | yes | The track you're mixing FROM — a catalog itunes_track_id, e.g. 'apple_ad1829eeccb70f9a'. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "score_transition",
    "arguments": {
      "to_track_id": "<to_track_id>",
      "from_track_id": "<from_track_id>"
    }
  }
}
```

## Why score_transition is rated Low

The tool reads metadata about two tracks (keys, BPM, energy) and computes a compatibility score through algorithmic analysis. It returns analytical results without creating, modifying, deleting data or executing code. This is fundamentally a read-only analysis operation with no side effects.

From the tool's own definition: "Tool performs scoring and analysis of track compatibility data ('Score how well one catalog track mixes into another', returns 'score', 'per-component scores', 'detail block', 'reason') — a calculation and retrieval operation with no modification, deletion,…"

## Use case

AI agents call score_transition to retrieve information from FreqBlog Music Metadata without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches FreqBlog Music Metadata:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "score_transition": {}
  }
}
```

## Other tools on FreqBlog Music Metadata (11)

- `build_setlist` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/build-setlist.md
- `find_compatible_keys` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/find-compatible-keys.md
- `find_tracks_by_bpm` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/find-tracks-by-bpm.md
- `find_tracks_by_key` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/find-tracks-by-key.md
- `get_audio_features` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/get-audio-features.md
- `get_audio_features_batch` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/get-audio-features-batch.md
- `get_recommendations` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/get-recommendations.md
- `get_related_artists` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/get-related-artists.md
- `search_catalog` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/search-catalog.md
- `suggest_next_track` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/suggest-next-track.md
- `tag_track` — Write — https://policylayer.com/tools/com-freqblog-music-metadata/tag-track.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=com-freqblog-music-metadata · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/com-freqblog-music-metadata